Such a process is known, for example, from Patent Application PCT/SE 93/00204.
In the known processes the interior of a hot air oven is heated to a required temperature. Then the foodstuff to be prepared, for example, deep frozen chipped potatoes, is put into a wire basket which can be introduced into the interior and is thus introduced thereinto.
The interior is then cooled, due to the low temperature and the high thermal capacity of the deep frozen foodstuff. For this reason the oven heating system is switched on and an air flow is created inside the oven by a hot air fan. The hot air flow heats the foodstuff by passing through the rotated wire basket containing the foodstuff. When the adjusted required temperature is reached, normally 230.degree. C. in the case of chipped potatoes, the oven heating regulating system begins to keep the temperature constant. At this temperature the so-called steam phase also begins, in which the foodstuff is refined in the oven atmosphere. The moisture escaping from the foodstuff remains in the interior of the oven and thus produces a damp hot oven atmosphere. In the steam phase the introduced foodstuff is merely refined and not browned, since in view of the high moisture no roasting starts on the surface of the foodstuff.
After a predetermined period in the steam phase, which depends on the mass and temperature of the foodstuff introduced and which can be calculated, for example, from the drop in temperature at the start of the process, the interior or refining chamber of the oven is aerated via an air supply channel and vented via an air discharge channel, so that the moist atmosphere can escape and a dry atmosphere be set up. With the required temperature further maintained, the preceding steam phase is followed by a roasting phase in which the foodstuff to be prepared is browned and made crisp by the roasting operation taking place in the dry atmosphere. On conclusion of the roasting phase the preparation of the foodstuff is completed, the oven heating is switched off and the foodstuff can be removed.
In the catering field the object of the prior art process is to achieve as high a throughput of foodstuffs per apparatus used as possible. To this end the objective is preparation times as short as possible.